1. Field of the Invention
The invention is based on a pressure regulator, in particular for a fuel injection system of an internal combustion engine, in which a pressure difference prevailing between a pressure inlet and a pressure outlet can be kept essentially constant by opening and closing at least one valve, which valve includes a valve closing member forced into the closing position against a valve seat by the action of a valve closing spring.
2. Description of the Prior Art
One pressure regulator of the type with which this invention is concerned, is known from European Patent Disclosure EP 0 198 381 A3, in which an elastic rubber diaphragm is retained between two housing halves of the pressure regulator and divides the housing into two chambers sealed off from one another. The diaphragm supports a cage that receives a valve ball associated with a valve seat. The valve seat is embodied on the end of a tube protruding into the lower housing half, which tube forms the pressure outlet of the pressure regulator. The cage is forced in the direction of the valve seat by a helical spring braced on the upper housing half. In addition, a further helical spring, braced on the cage, tenses the valve ball against the valve seat. Functioning as a pressure inlet is an opening, formed in the lower housing half, that communicates with a fuel pump. The upper chamber is subjected to the pressure prevailing in the air intake line of the internal combustion engine, by way of an opening in the upper housing half. When the fuel pump is put into operation, fuel is pumped via the pressure inlet into the lower housing half, and as a result of the pressure building up, the diaphragm is forced upward along with the cage, counter to the action of the helical spring; the valve ball is lifted from the valve seat and uncovers a flow cross section between the valve ball and the valve seat. If the pressure in the air intake line and thus also in the upper chamber changes, the diaphragm is moved upward or downward, causing the valve ball to move toward or away from the valve seat, which likewise causes a change in the flow cross section. The pressure difference that comes to be established between the pressure inlet and the pressure outlet should ideally change not at all or only slightly as a function of the volumetric fuel flow through the valve. To achieve this, the diaphragm must have a relatively large pressure-engagement area, which adversely affects the structural size of the pressure regulator. Moreover, there is the risk that over time the elastic membrane will tear or will no longer reliably perform its sealing function.
The pressure regulator of the invention has the advantage over the prior art that it makes do without a diaphragm and is therefore substantially smaller in size. In addition, it is more simply constructed as a typical pressure regulator and can therefore be produced more economically. Furthermore, the durability and reliability of a valve leaf spring are as a rule higher than those of a rubber diaphragm. The valve leaf spring is supported on the order of a rocker and is prestressed against the valve closing member by being braced on a support or clamping element. If a fluid pressure that generates a pressure force greater than the prestressing force acting on the valve closing member prevails at the pressure inlet, then the valve closing member lifts from the valve seat and uncovers a certain flow cross section, so that fluid can overflow to the pressure outlet. Because of the elastic properties of the leaf spring, the flow cross section can increase as the volumetric fluid flow increases, while the pressure difference between the pressure inlet and the pressure outlet changes only slightly, as in the pressure regulators of the prior art.
In accordance with a preferred embodiment, the valve leaf spring is pivotably connected to a pivot shaft, supported in a pressure regulator housing. The shaft has its axis disposed transversely to the length of the valve leaf spring and perpendicular to a plane that contains a center axis of the valve seat. A prestressing force generated by the support body can be transmitted as a closing force to the valve closing member by the valve leaf spring. The L-shaped cross section of the valve leaf spring makes for an especially compact design.
A further refinement provides that the support body is formed by a clamping leaf spring, which with its curved end is retained, in prestressed fashion, in the pressure regulator housing against the arm of the valve leaf spring located on the side opposite the valve seat. Because of the clamping leaf spring, additional spring-elastic resiliencies are present in the system, and the response behavior of the pressure regulator can therefore be still more sensitive, while pressure changes under conditions of a varying volumetric fluid flow are largely suppressed.
In a further, especially preferred provision, it can be provided that the valve ball can be retained with prestressing between a retainer leaf spring and the valve leaf spring; a ball segment of the valve ball, which segment is associated with the valve seat, protrudes through a through opening, oriented coaxially to a center axis of the valve seat, of the retainer leaf spring. As a result, the valve ball is durably retained between the two prestressed leaf springs, and in particular is retained in its opening position in a defined position relative to the valve seat. Furthermore, very high tightness and closing security are obtained; because the position of the valve ball is always stable, opening and closing positions of the valve body that are replicable at any time are assured for the pressure regulator of the invention. Since the valve leaf spring itself takes on some of the retention function of the valve ball, no additional components for guiding it are needed.